Loading-coil.



W. FONDELLER.

LGADiNG COM,

APPLICATION man :um 21. 3916.

1 52 1 Patented Jan. 2, 1917.

OKQ/Md UNITED STATES PATENT OFFICE.

WILLIAM FONDILLER, OF NEW YORK, N. Y., AssrGNoR TowRs'rnRN ELECTRICCOMPANY, INCORPORATED, on NEW YORK, N. Y., A CORPORATION OF NEW YORK;

LOADING-COIL Application filed June 21, 1916.

T 0 all whom it'm ag concern State of New York, have invented certainnew and useful Improvements in Loading- Coils, of which thefollowing isa full, clear, concise, and exact description.

This invention relates to loaded telephone lines, and more particularlyit relates to an improved form of loading coil to be used for loadingphantom telephone lines. Its object is the reduction of crosstalk inphantom line systems.

It has hitherto been proposed to load a phantom circuit according to thesystem described in the Campbell and Shaw Patent No. 980,921, by the useoi? loading coils with discontinuous magnetic cores; that is, coreshaving small non-magnetic gaps. Such coils have been found effective tominimizeto a large eXtent unbalaneesin line impedance caused by themagnetizing effect of strong foreign currents, such as lightningdischarges, to which the telephone lines may be exposed. A descriptionof such so-called air-gap coils and of their adaptation to the use inquestion will be found in an applica-.

tion for Letters Patent of Shaw and F ondiller, Serial No. 861,421,filed September 12, 1914;.

This invention provides an improved winding arrangement for such air-gapcoils, and consists in so proportionin'g the inner and outer windings ofeach core section that the mutual inductances between the windings whichare in series with one physical circuit and those which are in series.with the other physical circuit are balanced, thereby eliminating to alarge extent any danger from crosstalk in the coil itself.

The invention will be more clearly under reference to the accompanyingdrawing. I L

In the drawing, 1 and 2 represent the line conductors oi one physicalcircuit, and 3 and 4 represent the line conductors of another physicalcircuit which are combined in the usual manner, not here shown, toproduce phantom circuit.

5 is a loading coil with windings connect-- ed in series with each oneof the four line conductors in such a manner as to add in ductance t0the phantom circuit without adding inductance to the component physi-Specification of Letters Patent,

Patented Jan. 2, 1917.

Serial No. 105,035.

cal circuits. The core of the coil 5 is divided into two sections, eachcomprising two quadrants, (S and 9, and 7 and 8, respectively, thesections being separated at their extremities by non-magnetic gaps 10.Each quadrant is provided with an inner and outer winding; for example,quadrant 6 has an inner winding 11 and an outer winding 12; quadrant 7has an inner winding 13 and an outer winding 14-; quadrant 8, has aninner winding 15 and an outer winding 16, and quadrant 9 has an innerwinding 17 and an outer winding 18. Each line conductor is connected inseries with an outer winding of one quadrant and an inner winding of theopposite quadrant; for example, line conductor 1 is connected to one endof the winding 12, the other end of which is connected to one end of theinner winding 15 on the quadrant 8, the other end or said winding beingconnected to line again. The windings on the diiferent quadrants areconnected in such a way that when phantom circuit currents flowtherethrough, the magnetizing effect of the windings will be cumulativeto cent quadrants, for example, quadrants 6' and 7, it has been iouud,where the inner and outer windings have the same number o'l turns thatthe mutual. inductance of two outer windings, l2 and 1 1, is greaterthan the mutual inductance of two inner windings, 11 and 13. It has alsobeen found that the mutual inductance of an inner winding 11 of onequadrant, and an outer winding 14 o l an adjacent quadrant isintermediate betwecr the. mutual inductance of the two inner' windingsand the mutual inductance of the two outer windings, but that it isnearer the latter. The same condition obtains with reference to thewindings on adjacent quadrants of the same section, such as, quadrants 7and 8, though in this case the absolute values oi the inutuelinductences are greute than in the case where the quadrants sepers ed byon The unbalance mutual inductunces thus introducco has been 1:, foundto be :1 cause crosstalk in sir-gap oepend on runny factors, such as thesize, shape and materiel oi the core and the nuinher and dimensions ofthe air-gaps, in general, however, a gproper balance of the inntuelinductsnces will obtain it the deviation v of the mutual lllClllCtlllCQbetween on inner Winding of one quadrant and the outer winding or. anadjacent quadrant from the mean of the mutual indiiictunce of the twoouter windin s and the mutual inductance of the two ll'lLol windings oi?said quadrants some, in absolute value, regardless whether thesequadrants are separated sir-wipe or not. I A. convenient way ofrealizing this c0ndition is to, that this deviation shall be zero, 6.8., considering any two adincent quadrants, the mutual inductance the inner winding" of one quadrant and the outer winding of other quadrantshall be so i or approximately equal to the mean of 1e mutual inductanceof the two inner nd the niutuei inductance of the two outer wind-- ings.

lin e specific case in which this winding arrangement has been appliedto u coii for loudii" a phantom circuit, it has been found ratio of 1.03to 1 has been effective produce the desired degree of mutual inductancebalance in the coil, to effectiv y minimize the cross-talk danger.

W is claimed is:

1. loading coil having a magnetic core, i ne windings in a plurality oflayers on e. plurality of sections thereof, some of said sections beingseparated by non-magnetic gens, each line conductor through the coilincludi' windings in. different layers on opposite core sections, theratio of turns in said diii'eren layers being so proportions that themutual inductance between windot one layer on one section and wind-- inge. ditterent layer on on tion shell deviate "from the mean of the runtuel inductences between two windings of first layer on said ad acentsections the two windings ct said different coil having a magnetic core,

inner and on wine: 3 on plurality of sections of s: it. core, nonmagnetic sepu z ting some of said sections, each line condue-tor throughthe 0011 including an inner winding on one core section and an outerwinding on the opposite core section, the rutio of tu 1S in s-iiid i rand outer windings being such that t e deviation of the mutualilflCllllCllftllCE between an inner windof one section and an outerwinding" of L on adjacent section from the mean of the uni inductance ofthe two inner windings and the mutual inductance of the two outer"windings oi? said sections is the same, in

absolute value, regardless of whether said one section, and the windingof a. ditierent er on on. i gucent section shall be sous-l sdjuce;sections and the two windings of said difierent layer u said sections.

[1. loading" (301i liming a magnetic core with non-niaunetie inner andouter windings on o. plurality of sections of said core, each lineconductor through the coil including an inner winding on one coreseetion and an outer windi-.. on the oncoz: Li.

' site core section, ratio of turns in 'seid inner and outer windingsbeing so reportioned that the mutual inductance between an inner windingof one section and an outer Winding of an adjacent section 1 way betweenthe mutual inductance ot the two outer windings adjacent sections endwindings of said adjacent sections.

line conductors comprising two ph ysicel circuits, u loeding coil foradding inductance to said line conductors when phantom circuit prisingannular core, nonmagnetic gens divi core into equal. sections of two ieach, on inner and an outer windquadrant, each line conductor coil ieluding an outer windof one quadrant one. inner winding re opposite quotnt, the tour windings one hys i circuit being located on oputs, the fourwindings of the '"cuit heir locutedon the lrui s, the of turns in positsone l other ph s to the moon of too mutual inductunces he-' tween thetwo windings oi the first layer on 9 current flows therein, said coilcont;

' unity, 1

cuit current flows therein, said coil comprising an annular core,non-magnetic gaps dividing said core into equal sections of twoquadrants each, an inner and an outer winding on each quadrant, each,line conductor through the coil. including an outer winding of onequadrant and an inner winding of the opposite quadrant, the fourwindings of one physical circuit being located on opposite quadrants,the four windings of the other physical circuit being located on theother two opposite quadrants, the ratio of the 'number of turns in theinner windings to,

the number of turns in the outer windlngs being such that the deviationof the mutual inductance between the inner winding of one quadrant andthe outer winding of an adjacent quadrant from the mean of the mutualinductances of the two inner windings and two'ou'ter windings of saidadjacent quadrants is the same in absolute value regardless'oi whethersaid quadrants are on the same or different core sections.

7. In a loaded phantom line system, four line conductors comprising twophysical circuits, a loading coil for adding inductance to said lineconductors when phantom circuit current flows therein, said coilcomprising an annular core, non-magnetic gaps dividing said core intoequal sections of two quadrants each, an inner and an outer winding oneach quadrant, each line conductor through the coil including an outerwinding of one quadrant and an inner winding of the opposite quadrant,the four windings of one physicalvcircuit being located on oppositequadrants, the four windings of the other physical circuit being locatedon the other two opposite quadrants, the ratio of the number of turns inthe inner windings to the number of turns in the outer windings beingsuch that the mutual inductance between an inner windin on one quadrantand an outer winding on an adjacent quadrant is midway between themutual inductance of the two inner windings and the mutual inductance ofthe two outer windings of said adjacent quadrants.

In witness whereof, I hereunto subscribe my name this 20th day of June,A. D. 1916.

WILLIAM, FONDILLER.

